Notation 3.5 [1]}
Let \(\mathcal {T}_{\text{cyl}}\)  denote the class of cylindrical test functions consisting of the real-valued functionals \(\Phi =\Phi (u)\)  that depend on a finite number \(k\in \mathbb {N}\)  of components of \(u\) , that is,
\(\Phi (u)= \varphi \bigl ((u,g_1),\dots , (u,g_k)\bigr ),\) 
